1. Field of the Invention
One disclosed aspect of the embodiments relates to a recording apparatus and a recording method.
2. Description of the Related Art
A recording apparatus that completes an image on a recording medium by discharging inks onto the recording medium while scanning a recording head including a plurality of discharge port arrays corresponding to the different inks, each port array having a plurality of discharge ports for discharging inks having the same color arranged in a predetermined direction and intersecting the arrangement direction of the discharge ports, has conventionally been known.
In the above-mentioned recording apparatus, an improvement in recording speed has been required in recent years, and the recording head has been lengthened in keeping with the requirement for the improvement. As means for lengthening the recording head, portions (hereinafter referred to as overlap portions) capable of recording the same pixel row on the recording medium from predetermined numbers of discharge ports arranged at ends of the two discharge port arrays, which are adjacent in the arrangement direction of the discharge ports for discharging the same inks are provided. Thus, a recording head (hereinafter referred to as a joint head) is configured to have a plurality of discharge port arrays sequentially arranged therein along the arrangement direction of the discharge ports. The recording head can be lengthened by arranging a plurality of short discharge port arrays when the joint head is used.
When an image is recorded using the joint head, unevenness may occur in an image area on the recording medium recorded by the discharge ports arranged in the overlap portion, causing deterioration in the quality of the image. The unevenness includes unevenness caused by an error in mounting of the discharge port arrays and an error in manufacture of the discharge ports and unevenness caused by different timings for discharging inks from the respective discharge ports arranged in the discharge port arrays which constitutes the overlap portion.
United States Patent Publication Application No. 2004/0218200 discusses the technique which regularly varies in an arrangement direction a boundary between an area where recording is performed only by discharge from discharge ports in one of two discharge port arrays constituting an overlap portion in a joint head, and an area where recording is performed only by discharge ports in another discharge port array, as the boundary moves in a scanning direction. As a consequence, unevenness occurring in an area on a recording medium corresponding to the overlap portion in the joint head becomes inconspicuous. Further, United States Patent Publication Application No. 2004/0218200 also discusses the technique in which, when a plurality of joint heads discharging different inks, is arranged in the scanning direction, shapes of respective boundaries in overlap portions in the joint heads are formed different from each other.
However, in recent years, a demand to improve an image quality of a recording image has increased. In a method discussed in United States Patent Publication Application No. 2004/0218200, a sufficient image quality may be unable to be obtained.
Such an issue will be described in detail below.                FIG. 1 illustrates an image recorded on a recording medium according to a conventional technique using a joint head.        
For simplicity, a joint head is used in which six discharge port arrays 22 are configured to have 50 discharge ports 30 arranged in a Y direction. while The three discharge ports 30 arranged at one end of one of the discharge port arrays 22 and the three discharge ports 30 arranged at the other end of the other one of the discharge port arrays 22 form an overlap portion 65 to record an image in the same area 68 on a recording medium 3. The discharge port arrays 22 are shifted in a predetermined direction to have a staggered shape.
The joint head 7 performs discharge from each of the discharge ports 30 arranged in the single discharge port array 22 onto an area 67 of the recording medium 3 corresponding to an area 66 other than the overlap portion 65. On the other hand, the discharge ports 30 respectively arranged in the two discharge port arrays 22 forming the overlap portion 65 share the area 68 on the recording medium 3 corresponding to the overlap portion 65 in discharging inks.
According to a method discussed in United States Patent Publication Application No. 2004/0218200, when recording is performed on a recording medium 3 using the above-mentioned joint head 7, ink discharge is controlled so that in an area 68a on the recording medium 3 corresponding to an overlap portion 65a of discharge port arrays 22a and 22b, a boundary 69a of dots formed by discharge from discharge ports in the discharge port array 22a and dots formed by discharge from discharge ports in the discharge port array 22b continuously vary, as illustrated in FIG. 1.
Further, in areas 68b, 68c, 68d, and 68e on the recording medium 3 respectively corresponding to overlap portions 65b, 65c, and 65d, and 65e, boundaries 69b, 69c, 69d, and 69e of dots corresponding to one discharge port array and the other discharge port array are also formed while continuously varying, so as to have similar patterns.
However, if a plurality of boundaries corresponding to a plurality of overlap portions in the joint head 7 is arranged in the same shape in the Y direction, as illustrated in FIG. 1, variation patterns 67a, 67b, 67c, 67d, and 67e of the boundaries mutually emphasize each other on the entire recorded image, and the boundaries are easily recognized as an visual image. Thus, when the entire image is viewed, unevenness occurring in the overlap portions in the joint head 7 may be sufficiently suppressed, causing deterioration in the quality of the image.